1. Field of the Invention
The invention relates generally to a method for enrichment and/or separation of uranium or other isotopes from isotopic mixtures and, more particularly, but not by way of limitation, it relates to an optical-discharge separation process for separation or enrichment of .sup.235 U from natural uranium.
2. Description of the Prior Art
Demands of the nuclear power industry require enrichment of uranium in its content of the .sup.235 U isotope, as such enriched uranium is used in power generating nuclear reactors. Since the advent of nuclear power capabilities, such uranium isotope separation for enrichment purposes was carried out by a process known as gaseous diffusion. The gaseous diffusion process is very electrical power intensive such that the cost of producing separative work units of enriched uranium has become extremely high due to the much increased cost of electricity and fuels used in generating electricity.
Other uranium separation processes are currently being developed. A process known as the gas centrifuge method is presently under construction and should be producing enriched uranium in commercial quantities in the very near future. This process uses centrifugal force to distinguish the slight difference in the weight of uranium hexafluoride molecules containing the .sup.235 U isotope from those with the more prevalent .sup.238 U isotope. As the stock material is rotated at extremely high speeds, the lighter molecules are concentrated near the axis of rotation whereupon they are caused to move preferentially downward for separation.
Yet another method of uranium enrichment is currently being developed for large-scale application at Lawrence Livermore National Laboratory and this process is termed atomic vapor laser isotope separation (AVLIS). The AVLIS process utilizes selective absorption of radiation of a particular energy level by the .sup.235 U isotope. The uranium metal is heated and vaporized for exposure to lasers of predetermined wavelength which selectively ionizes .sup.235 U atoms in successive steps. The ionized atoms are collected by electromagnetic fields to be formed into the enriched product while the neutral .sup.238 U atoms pass through the magnetic field for collection as tailings. The process uses such as pumped dye lasers in the visible spectrum.
Still other advanced isotope separation methods are under development such as a molecular laser separation method that utilizes dual laser irradiation for first excitation of the .sup.235 U containing molecules followed by a second irradiation to dissociate a fluorine atom from the excited molecules to produce enriched uranium pentafluoride as a finely divided solid. This powder is then refluorinated to produce uranium hexafluoride as the enriched product.
Finally, there is a process utilizing plasma separation which begins by vaporizing uranium metal for subsequent ionization into a plasma for inclusion into a high-strength magnetic field and subjection to an electric field tuned to the cyclotron resonance frequency of .sup.235 U ions. Absorption of energy by ions tends to increase the diameter of their cyclotronic paths so that the .sup.235 U ions are separable from the .sup.238 U ions by tangential interception.
All of the proposed advanced isotope separation methods have estimated readiness dates considerably in the future as far as operational application is concerned. None of the processes has been operated at full scale and it is forseen that there are many design and construction problems to be overcome.